How to predict arc flash

Mark Lant explains what you need to know to fully understand the risks and to predict when an arc flash incident is more likely to occur

Working around high and low voltage electricity on a daily basis means workers are at an increased risk of experiencing an arc flash. 

With temperatures that can reach up to four times hotter than the sun, an arc flash has the potential to cause fatal or life-changing injuries. So it goes without saying that prevention is fundamental to ensuring workers’ safety.  

1. Use arc flash studies 

An arc flash study is not only essential to calculate the level of PPE that needs to be provided for your team, but it is also a useful barometer to predict how likely an incident is to occur. 

Carried out by a qualified electrical engineer using dedicated software, these studies analyse the whole facility with an on-site evaluation. The study also utilises arc flash modelling and will use the results of a short circuit and coordination study. 

Once complete, the study will provide you with details of the potential incident energy (the measure of how severe an arc flash is) at each piece of equipment posing a risk, along with the incident boundary (how far away someone would need to be before PPE is needed). 

With this, the equipment can then be appropriately labelled and risk assessments can be carried out, which may result in different types and/or ratings of PPE being recommended. 

2. Utilise risk assessments

Anyone working in an operational role within the industrial electric sector will be familiar with risk assessments. They provide useful insight into the steps that organisations and team members need to take in order to keep themselves safe. 

To ensure they are constantly effective and incorporate best practice, risk assessments need to be regularly updated every five years, or whenever a major change is made to an installation.

Risk assessments will take some information from an arc flash study but tend to be specific to either an action or a piece of equipment. In short, an arc flash risk assessment will predict when an arc flash incident could occur by:

• Identifying a hazard
• Estimating the likelihood of an incident and the potential severity of injuries as a result (the risk)
• Recommending whether additional protective measures are needed

3. Fixed vs dynamic risk assessments  

It is widely recommended to carry out dynamic risk assessments as opposed to fixed risk assessments. This is simply because dynamic risk assessments are carried out at the time work is about to be undertaken, giving a more accurate measure of the risk posed on each piece of equipment. 

Adequate training for your electrical engineers will also help them to predict when an arc flash might occur. 

4. Understanding which activities are most risky

While most work undertaken in the XXX sector is considered a risk to some degree, identifying the dangerous activities can help to predict when an arc flash might occur, and therefore help to protect against it. 

Generally, in the context of an arc flash, the following activities are considered to fall under the bracket of ‘high risk’:

• Breaking ground – unfortunately, service maps are sometimes not accurate or out of date which can lead to cables or pipes being struck – a common cause of an arc flash blast.
• Energised equipment – it may seem obvious, but it’s important to recognise that with live power, there is a much higher chance of encountering an electrical incident like an arc flash. 
• Working in electrical cabinets – this is one of the places your team will most likely encounter an arc flash, with a high volume of reported incidents occurring while working in this environment.

5. Arc flash PPE – the last line of defence

Once the steps outlined above have been put into place and risks have been minimised, you must then ensure your team is provided with the bast possible last line of defence – the appropriate level of arc flash PPE. 

Details of an arc flash study will determine what cal rating of PPE that is needed to protect your workers and avoid serious injury from an incident. We would recommend arranging a consultation with expert arc flash PPE manufacturers, like ProGARM to gain support in selected work wear that will best protect your workforce. These consultations are held with no obligations and offer vital insight into the appropriate arc flash PPE requirements for each workplace. 

Mark Lant is a technical expert at ProGARM.